1. Technical Field
The present invention relates to a seat belt retractor for use in a vehicle. Particularly, the present invention relates to a seat belt retractor having a comfort mechanism to eliminate the force exerted by seat belt webbing against a vehicle occupant.
2. Description of the Prior Art
Seat belt retractors having comfort mechanisms for eliminating the force exerted by seat belt webbing against a vehicle occupant are known. One such seat belt retractor is disclosed in U.S. Pat. No. 3,682,412. The seat belt retractor disclosed in U.S. Pat. No. 3,682,412 includes seat belt webbing wound on a spool. The spool is supported for rotation in belt withdrawal and belt retraction directions. A return spring biases the spool to rotate in the belt retraction direction. The biasing force of the return spring tends to pull the belt webbing against the occupant, which may cause discomfort to the occupant. To avoid causing such discomfort, the retractor includes a comfort mechanism which, when actuated, blocks rotation of the spool in the belt retraction direction so the belt webbing is not pulled against the occupant.
The comfort mechanism disclosed in U.S. Pat. No. 3,682,412 is manually set. When the belt webbing is withdrawn from the spool and buckled around the occupant, the return spring rotates the retractor spool in the belt retraction direction to pull the belt webbing against the vehicle occupant. The vehicle occupant then withdraws the belt webbing a relatively small amount to establish slack in the webbing and actuates the comfort mechanism by moving a handle. Rotation of the spool in the belt retraction direction is then blocked and the slack in the belt established by the occupant is maintained.
In a nonemergency situation, if the occupant moves forward from an initial position, the slack in the belt webbing is taken up and the webbing is withdrawn from the spool and follows movement of the occupant. When the occupant moves back to the initial position, the spool rotates in the belt retraction direction, due to the bias of the return spring, to a position in which the slack in the belt webbing is reestablished. Thus, the retractor has a "memory" so that the amount of slack in the belt webbing set by the occupant is reestablished. The comfort mechanism includes a ratchet wheel connected to the spool. A pawl is pivotable into engagement with a tooth on the ratchet wheel to block rotation of the spool in the belt retraction direction. After slack is established in the webbing, the handle is manually moved to pivot the pawl into engagement with a tooth on the ratchet wheel. A spring is connected at one end to the pawl and at its other end to a shaft. When the belt webbing is withdrawn, for example, due to movement of the occupant forward from the seat back, gears rotate the shaft in one direction and the spring pivots the pawl away from engaging the tooth on the ratchet wheel. When the belt webbing then retracts onto the spool, the gears rotate the shaft in an opposite direction and the spring pivots the pawl toward the ratchet wheel to engage the tooth it previously engaged on the ratchet wheel and to reestablished the slack.